The Vocal Cords are the actual vibrating material of the Vocal Instrument, the origin of the sound. They are more appropriately called Vocal Folds. Although not everyone describes it this way, you can think of the Vocal Folds as the whole structure of tissue and muscle, and the Cords as the Ligament that lines the fold that acts as the vibrating edge. The Vocal Folds are located inside the Larynx attached to the Thyroid Cartilage at the front in a fixed closed position. They are attached in the back to the movable Arytenoid Cartilages. This allows them to open for respiration and close for phonation and to protect the air-way. They are the main line of defense for the Trachea and Lungs. This is their main purpose, to close during swallowing to block the windpipe from food and liquid. For communication, the Vocal Folds are the main source of sound in grunting, cooing, and crying in infants. This foundation of sound production is then developed into talking and singing.
The length of the Vocal Folds varies between 12.5mm and 17.5mm in females and 17mm and 25mm in males. These differences in length are partly responsible for the pitch range differences between men and women. The folds can also vary in thickness, which will also influence pitch range and quality.